"On this day ten years ago, the first prototype StrongARM processor card was powered up by Acorn engineers. The experimental kit managed to run at a cool 228MHz, running software nearly six times faster than the 40MHz ARM710 processors used in RiscPCs at the time. The card, which drew one watt of power, would later go on sale in September 1996."

Probably not. With current laptops, the CPU uses less than 30% of the power of the mcahine. Even if the CPU used 0 watts, a laptop would only go from (say) 3 hours to 4 hours. To hit 10 hours, you'd need to reduce power useage by about a factor of three across the board.

They did actually sell an Acorn laptop - my old music teacher had one, the battery life was pretty good; applications you needed resided in rom, fast boot and shutdown, heck, even had a PC emulator for basic dos and Windows 3.1 applications.